The present invention relates to a target for optically activated seekers and trackers and more particularly to a simulated target for testing optically activated seekers and trackers which provides for calibrated and variable target characteristics such as size, intensity, spectral emission, spatial position and interfering background.
An optically activated seeker is designed to detect and home-in on radiation, such as infrared or laser, reflected or emitted from a target.
Previously, a crude system of mounting a small lamp or diode, if the seeker was designed for a laser, on a plotting board was used for testing optically activated seekers. The plotting board was positioned 10 feet in front of the seeker, using the X-AND-Y motions to simulate target motion.
The plotting board system was disadvantageous in that the seeker had to be disassembled and focused for the test at a 10 foot distance, then disassembled and refocused after the test. In addition, the plotting board target could not provide for changes in target intensity or target size. More importantly, the plotting board system could not provide a competitive background to test the ability of the seeker to reject interfering targets.
Additional prior art target simulators for optically activated seekers are disclosed in U.S. Pat. No. 4,021,662 to Mimms and U.S. Pat. No. 3,857,042 to LaGrange et al.
The device of Mimms simulates a target for a laser seeker by means of a convex spherical mirror segment that reflects light from various point sources of light onto the light receiving aperture of a laser seeker. The point sources of light are positioned at the mirror focal point with one source at the laser seeker boresight and another source displaced from and rotatable about the first source. A continuous wave source of light is also provided. The target simulator of Mimms is provided with controls for coded operation and power level manipulation of the point sources of light. The simulator of Mimms does not provide for variations in target size or spatial position and also does not provide an interfering background for testing the ability of the seeker to reject interfering targets.
The laser seeker test set of LaGrange et al simulates a moving light emitting target by sequencing a plurality of small light emitting diodes at a rate not exceeding the tracking rate of the laser seeker being tested. Digital circuitry is used to determine the sequence and timing of the diodes and also provides for manually sequencing the diodes as desired. The diodes emit a collimated beam of energy at different angles to the longitudinal axis of the seeker. By observing the seeker with instrumentation, the tracking capability of the seeker can be determined. The simulator of LaGrange et al does not provide for variations in target size or intensity and again does not provide an interfering background for testing the ability of the seeker to reject interfering targets.